1. Field of the Invention
This invention concerns active substances to promote the coagulation of blood sampled for examination and, more particularly, it relates to coagulants which are used for separating serum or plasma (hereinafter referred to as serum) from the whole blood for testing the serum in a shorter time and at a higher yield and for use in hemostasis.
2. Description of the Prior Art
With the increase in the number of blood specimens to be examined, various studies have been made and put to practical use for improving the efficiency of separating serum from blood. Since the serum is mostly examined in the blood test, it is desirable to separate the serum from the whole blood with no contaminations in a short time and at a high yield. For the purpose of separation, it has been recognized as effective to use a so-called serum separating sealant of a high molecular substance for forming partitions such as silicones, or polyether resins and acryl resins as disclosed in U.S. Pat. No. 4,140,631 having an intermediate specific gravity between the liquid serum portion and the solid corpuscular portion (hereinafter referred to as a separating gel), as well as a blood coagulant in combination.
With the reason as described above, means for promoting blood coagulation are used for attaining the separation of the serum from the whole blood in a short time at a high accuracy. As the agents to be used for promoting blood coagulation, there have been reported, for instance, finely powderous or fibrous silicate compounds such as kaolin, Celite, diatomaceous silica and glass fibers, fine powders of calcium compounds such as calcium carbonate and calcium sulfate, thrombin-like substances derived from snake venoms, and polyphenols that can activate blood clotting factors to promote the coagulation. Further, there have been reported various methods of using these substances, for example, adding one or more of them into a blood to be separated, coating them to the inside wall of a serum separation test tube, coating or depositing them onto an appropriate carrier which is then placed in the test tube, or dispersing them in the separating gel.
However, if the coagulant is dispersed into the separating gel, no satisfactory effect of promoting the coagulation can be obtained because of reduction in the contact between the coagulant and the blood and hemolysis may sometimes be caused during centifugal separation of the blood.
Coagulants derived from snake venoms involve problems in that they are effective only for a short period of time and are expensive as well. Other coagulants may also cause problems in that the coagulation time can not be shortened as expected, and impurities are introduced into the serum.